How do you scale both sides in axis Z while the other side is less affected?
If you're referring to creating this effect with a mesh, you could use an array with a custom object offset, like in this blend here:



All you need is a Plane (Or Cube) plus an empty. The empty should be created at the origin of the Cube to easily understand how the effect works. Then, add an array modifier to the cube. 



Instead of using the Relative Offset, which is the default, you can use the object offset and choose the Empty. Now, each element of the array receives the Transform differences between the cube and the empty. Move the empty to the side a bit, and you'll see what it means. If you now scale the empty only in the Z direction, you get the effect which (I think) you want. Each array element is a scaled down version of the element before. So the first one has Z = 0.9, the second one Z = 0.9 * 0.9, and so on.

To put it on a circle, use 'Simple Deform' or curve modifiers, whatever works best for you.